This invention relates to coating compositions, and more particularly to water based silicone coating compositions that offer superior coating properties, resistance to high temperatures and to the effects of corrosive environments and durability. The present invention provides water based silicone coating compositions, methods for producing such compositions, as well as high temperature heat exchangers whose surfaces are coated with such water based silicone coating compositions.
Silicone resins are known to demonstrate endurance towards environmental conditions such as weathering and extreme heat and cold. For this reason these resins have been found to be particularly useful in the paint industry.
Previously, silicone resins were made available to formulators in organic solutions. In particular, the resin consisted of so many parts by weight of silicone solids in an organic solvent such as xylene or toluene. However, due to increased concerns regarding: the suspected health hazards to persons exposed to such solvents; environmental considerations and the mandatory use of costly and burdensome pollution abatement procedures and equipment; and escalating costs for organic materials, the use of such organic solvents has been discouraged. As a result, suppliers of these silicone resins have worked towards developing silicone resin systems that are water based and therefore not dependent upon organic solvents.
Yet, such silicone resins which have been found to be particularly useful in the paint industry have often been found to be immiscible or otherwise incompatible with aqueous coating compositions. For those silicone resins which can be made part of water based emulsions which can then form the basis of a paint or coating composition, the ability of these coatings to generally match the performance (e.g., coating properties) of other temperature-resistant protective coatings is oftentimes not realized. Moreover, such compositions do not serve to adequately protect the underlying substrate from the effects of corrosive environments.
For devices such as high temperature aluminum heat exchangers which have an intricate network of passages therethrough and which are oftentimes subjected to corrosive environments, the deficiencies of prior art water based coating compositions take on significant proportions.
It is, therefore, an object of the present invention to provide water based silicone coating compositions that offer superior coating properties and resistance to high temperatures.
It is another object of the present invention to provide novel coating compositions that exhibit durability and resistance to the effects of a corrosive environment.
It is yet another object to provide a process for producing such water based silicone coating compositions.
It is still another object of the present invention to provide a high temperature heat exchanger whose surfaces are coated with such water based silicone coating compositions.